1915-2-18 Unrestricted Submarine Warfare

1915-2-18 Germany begins unrestricted submarine warfare during WW1 - HiPo > .

On the 18th of February 1915, Germany initiated a policy of unrestricted submarine warfare during WW1.

Prior to the introduction of unrestricted submarine warfare, submarines adhered to ‘cruiser rules,’ which required them to surface and provide warnings to merchant and passenger ships before launching an attack. However, faced with the British naval blockade and desperate to cut off vital supplies to the Allied forces, Germany opted for a more aggressive approach.

On February 4, 1915, Admiral Hugo von Pohl of the German High Seas Fleet warned that ‘every enemy merchant vessel’ in British waters would be targeted and that ‘it may not always be possible to prevent attacks on enemy ships from harming neutral ships’.

This shift in naval tactics was a response to the increasing effectiveness of the British blockade. This was impacting Germany’s ability to sustain its war effort so, by targeting merchant ships including those of neutral nations, Germany aimed to undermine the economic foundations of the Allied powers in return.

The decision, however, had severe consequences. The sinking of civilian vessels, such as the ocean liner RMS Lusitania on May 7, 1915, with the loss of nearly 1,200 lives including 128 Americans, intensified global outrage.

Facing the risk of drawing neutral nations into the war, unrestricted submarine warfare was essentially abandoned on 1 September. However, facing an increasingly desperate situation, on 31 January 1917, Kaiser Wilhelm signed an order for unrestricted submarine warfare to resume the following day. President Wilson of the USA subsequently severed all diplomatic relations with Germany, and the US Congress declared war on 6 April.